Change speed gear for bicycles



Jan. 16, 1940. o. TODRYS v CHANGE SPEED GEAR FOR BICYCLES Filed Oct. 7, 1939 32 OTTO TODRYS VINVENTOR v BYW MAL/V ATTORNEY all patented Jan. 16, 1940 UNITED STATES CHANGE SPEED GEAR FOR BICYGLES- Otto Todrys, New York, N.Y., assignor to France Sporting Inc New York, N. Y., a, corporation of New York Application October '7, 1939, Serial No. 298,418

2 Claims.

This invention relates to. improvements in changespeed gear mechanism for bicycles and the like and more particularly to mechanism of the type in which the driving chain is moved from one to another of different sized sprockets by transverse displacement by a jockey sprocket.

In the usual construction of changeable speed gear mechanism for bicycles, diificulty has been found in alining the movable shifting housing with the stationary rocker bracket with the result that a very great force was required for actuating the flexible cable and the attached chain. An object of this invention is to provide im proved means for facilitating the alignment of the movable shifting bracket with the stationary bracket so as to minimize the pulling force required for the chain.

Another object of this invention resides more particularly in the special construction and disposition of the aligning means for actuating the co acting parts in parallel relation and whereby the driving chain may be selectively engaged with any one of. a plurality of diiferent sized sprockets on the driving wheel hub so as to obtain the desired speed ratio with ease.

With the above and other objects in view, the invention will be hereinafter more particularly described, and the combination and arrangement of parts will be shown in the accompanying drawing and pointed out in the claims which form part oi this specification,

Reference will now be had to the drawing, wherein like numerals of reference designate corresponding parts throughout the several views, in which:

Figure 1 is a fragmentary side e evation of the mechanism and parts of the him i Figure 2 is a front elevation of the mechanism shown in Figure l. i

Figure 3 is a rear elevation of the mechanism on enlarged scale and partly section.

Figure 4 is a cross-sectional view of the jockey sprocket mounting.

In the illustrated embodiment of the invention, the numeral it indicates a change speed gear mechanism comprising a bracket arm ll Xed to the frame it of the bicycle. Mounted on a pivot H3 at the lower end of the arm it is a rocker bracket M having secured thereto a tubular member 15. The tubular member it is in parallel relation with the pivot l3 and has an elongated thread It. Slidably mounted in the tubular member 15 is a spindle ll having a jockey sprocket l8 rotatably mounted thereon. The

jockey sprocket 18 has an outwardly tapering periphery adapted ior engagement with a sprocket chain 19.

Rotatably mounted on the axlettl is a set of interconnected sprocket wheels .21, 22 and 23 of different diameters. The chain til is long enough to engage the jockeysprocket and one of the said sprocket wheels, A coil spring mounted on the pivot iii has one of its ends 2ft hooked to the rocker bracket i l and the other end hooked in a slot 2! in the pivot it. The pivot 53 is fixed to the bracket arm ll, but is rotatable in the rocker bracket id. The spring is tensioned in a direction. tending to press the rocker bracket to the left of the position shown in Figure l and this motion tightens the chain it irrespective of the diameter of, the sprocket wheel with which the chain is in engagement.

As shown in Figure 4, a conical coil spring 28 has been mounted on the spindle ill. The spring 23 reacts against the rocker bracket i land presses against a shifting housing 29 in which the spindle it has been mounted and forces the housing away from. the rocker bracket it and moves the jockey sprocket in a direction transverse to the frame of the bicycle.

As shown in Figure 3, the transverse displacement of the shifting housing 353 is limited by the length of the body of a guide rod 3ft designed for sliding movement through an aperture 32 in the inner arm 33 of the housing. The head M of the guide rod is larger than the body 36 and acts as a. stop against further separation of the members hi and 33.

For the purpose of this invention which is to facilitate the alignment of the movable shifting bracket 29 with the rocker bracket M, I have provided an elongated sleeve 35 integral with the inner arm 33 and in contacting slidable relation. with the body of the guide rod til. The elongated sleeve is of a length to engage a substantial portion of the rod body and provides a long bearing surface which retains alignment of the stationary and moving parts.

As shown in Figure 4, I have provided a circular receiving channel 3% in the rocker bracket l4, and a circular receiving channel 3T1 in a threaded member 38 in fixed relation with the inner arm 33 of the housing 283. The channels 36 and El are in concentric relation with the spindle H. A spiral spring 39 made or ribbon-like spring steel and arranged with the successive coils in contacting relation has been mounted in. the chan-- nels 36 and 31. The spring 39 forms a reinforcing housing for the spindle il During all movements of the shifting housing 29, the two circular channels 36 and 31 are retained by the spring 39 in central alignment and this augments the alignment of the stationary and movable parts.

I have provided a bushing 40 having a comparatively large radius at the outer end and forming a bell-mouth opening. The bushing 40 has been fixed in the rocker bracket with the large radius facing outwardly. The bell-mouth outer surface contacts with a comparatively long surface of the chain 4| in all positions of adjustment and facilitates the movement of the chain while under stress, that is, the bell-shaped mouth prevents point contact between the chain and the surface of the chain aperture in the rocker bracket.

The control chain 4| has been mounted in eccentric relation with the spring housing 39 and in eccentric relation with the jockey sprocket. The application of the chain 4| is at a point intermediate the spindle H and the line of motion of the sprocket chain l9. This intermediate position of the chain 4| balances the control chain pull on the return spring 28 and the frictional drag of the sprocket. chain against the shifting housing and augments the alignment of the stationary and movable parts.

In operation, a pull on the wire 42 by means 4 Well known in the art, causes the control chain 4| to shift the jockey sprocket i3 sideways and this motion draws the driving chain l9 sideways which thus jumps from one sprocket wheel to another. The spring 25 tensions the rocker bracket l4 and takes up the slack in the driving chain.

I claim:

1. In a change speed gear mechanism of the class described, comprising a shifting housing in which a jockey sprocket is rotatably mounted on a spindle and being movable to and from a rocker bracket, a tubular member secured to said rocker bracket and in engagement with a spindle secured to said shifting housing, said shifting housing and said rocker bracket having circular channels concentric with said spindle, and a spring reinforcing housing made of ribbonlike spring steel with the coils in contacting relation and seating in said channels for augment ing the alignment of said shifting housing with said rocker bracket.

2. In a change speed gear mechanism of the class described, comprising a shifting housing in which a jockey sprocket is rotatably mounted on a spindle and being movable to and from a rocker bracket, a tubular member secured to said rocker bracket and in engagement with a spindle secured to said shifting housing, said shifting housing and said rocker bracket hav-- ing circular channels concentric with said spindle, a reinforcing housing made of ribbon-like spring steel with the coils in contacting relation and seating in said channels, a guide rod secured to said rocker bracket and being in slidable engagement with an elongated sleeve integral with said shifting housing, said elongated sleeve being in spaced parallel relation with said reinforcing housing and serving to align said shifting housing with said rocker bracket in all of their relative slidable positions.

OTTO TODRYS. 

